This invention concerns N-substituted succinimides, their manufacture and use as additives for gasoline and the resultant improved gasoline compositions having good anti-rust and detergent properties in the carburetor or in the intake systems.
Erratic idling and stalling of the combustion engines operating with a carburetor are well known as difficulties associated with the driving of motor cars.
One of the reasons of the erratic idling and of the stalling of the engine is the accumulation of deposits on the throttle valve of the carburetor and on the surrounding walls.
The accumulation of deposits impedes the normal flow of air through the carburetor and consequently results in the formation of rich fuel mixtures. The deposits may be formed, for example, by accumulation of impurities or dusts from air or from the recycle gas from the engine housing.
Moreover, these mixtures of very high fuel content burn incompletely and accordingly increase the air pollution by discharging thereinto an increased proportion of partly burnt fuel particles.
The modern carburetors of large capacity have a complex structure. Even small amounts of deposits and residues, when present in the fine control members of these carburetors highly disturb the operation of the latter and result, in particular, in a bad composition of the fuel/air mixture for which the ratio CO/CO.sub.2 increases.
In order to obviate these disadvantages it is necessary either to proceed periodically to an expensive cleaning of the carburetor and of the intake valve heads, or to increase the normal idling running speed with the consequence of a more difficult driving of the vehicle and a useless increase in the fuel consumption.
It is known to reduce or to prevent the accumulation of these deposits in the carburetor by making use of fuels containing additives called detergents for carburetors.
In addition to these detergent additives for carburetors, the modern fuels require further additives for improving the behaviour of the fuel, such as anti-rust additives and additives for reducing the deposits in the admission system. Preferably multifunctional additives are used.
Although many multifunctional additives have been proposed in this technical field, many of them are not acceptable as a consequence either of undesirable effects of their use or of the excessive amount of additive required for obtaining the desired properties.